EARTHQUAKES

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EARTHQUAKES

• SHAKE, RATTLE, ROLL AND DESTROY!

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SEISMOLOGY

• THE STUDY OF EARTHQUAKES
• THE SCIENCE DEALING WITH ALL EARTH MOVEMENTS AND
  WAVES

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SEISMOLOGIST

• THE SCIENTIST THAT STUDIES THE MOVEMENTS OF THE
  EARTH
• A PERSON WHO STUDIES SEISMOLOGY
• MUST KNOW FACTS ABOUT GEOLOGY, PHYSICS, AND
  CHEMISTRY

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SEISMIC WAVES

• CALLED EARTHQUAKE WAVES
• THERE ARE THREE TYPES OF SEISMIC WAVES
• PRIMARY WAVES (P-WAVES)
• SECONDARY WAVES (S-WAVES)
• LONGITUDINAL SURFACE WAVES
• (L-WAVES)

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SEISMOGRAPH

• THE INSTRUMENT THAT MEASURES AND COLLECTS SEISMIC
  WAVES FOR EACH EARTHQUAKE.
• IT SENDS THESE WAVE VIBRATIONS TO THE PRINTER
  MACHINE WHICH CREATES A GRAPH TO VIEW THE
  LOCATION OF THE SEISMIC WAVES

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SEISMOGRAM

• THE GRAPHED DRAWING OF THE EARTHQUAKE WAVES
  CAUGHT BY THE SEISMOGRAPH.
• SHOWS THE LOCATIONS OF MANY DIFFERENT SEISMIC
  WAVES SO THAT SEISMOLOGIST CAN DETERMINE WHERE,
  ON EARTH, THE EARTHQUAKE OCCURRED.

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HOW TO REMEMBER THE 5 SEISMIC WORDS

• A SEISMOLOGIST STUDIES
• SEISMOLOGY, WHICH INCLUDES
• SEISMIC WAVES THAT ARE CAUGHT
• BY A SEISMOGRAPH MACHINE,
• WHICH GRAPHS THE WAVE
• LOCATIONS ON A SEISMOGRAM.

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What are earthquakes?

• An earthquake is a sudden shaking of the ground.
• Earthquakes are the result of the movement of
  the earths surface, also called the lithosphere.

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Lithosphere Earth Plates

• The lithosphere is made up of both the crust of
  the earth and the upper mantle.
• Earth plates are puzzle pieces on the earth that
  make up the lithosphere.
• These plates float on top of another layer of
  the earth called the liquid rock mantle, causing
  them to move.

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Lithosphere and Mantle
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The Puzzled Earth
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The Outer Layers of the Earth
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Convection Current models

• This movement of heat energy causes the tectonic
  plates to move.

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Whose Fault Is It?

• Faults are the cracks located in between earth
  plates.
• They can be up to 10 miles deep.
• Movement of the lithosphere occur along faults.
  This movement results in an earthquake.

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4 Types of Faults

• Normal fault
• Reverse fault
• Lateral fault
• Thrust fault

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Normal faults

• A normal fault occurs when one plate slides down
  another plate.
• They result in extension (the plates move
  apart).

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Reverse Faults

• Reverse faults occur when one plate slides up
  another plate.
• The angle is steep usually greater than 45
  degrees.
• They result in compression and shortening of the
  plates.

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Lateral Faults

• Lateral faults occur when one plate slides either
  to the right or to the left of another plate.

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Thrust Faults

• Thrust faults are a type of reverse fault.
• They occur when one plate slides above another
  plate.
• They are not as steep, so they are smaller
  than 45 degrees.

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Mid-Atlantic Ridge

• The Mid-Atlantic Ridge is a mostly underwater
  mountain range where tectonic plates pull apart.
• As they pull apart, magma rises to fill in the
  cracks. It then causes the crust to expand,
  resulting in the mountain ridges.
• The highest peaks of this mountain range form
  islands.

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Location of the Mid-Atlantic Ridge
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San Andreas Fault

• It is more than 800 miles long and 10 miles deep!
• It is an example of a lateral fault.
• Locked sections remain still for about hundred
  years until there is enough force to move them.
  These sections result in massive earthquakes.
• Sections that creep move slowly at a constant
  rate. They result in more subtle earthquakes.

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San Andreas Fault

• Geologists have found that the movement of the
  earths surface, due to the earthquakes and
  constant creep along this fault, has been about
  350 miles since it has existed. We are talking
  about 15-20 billion years ago!
• This fault moves the earths surface at about 2
  inches each year.

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Images of the SAF
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The Future of CA
The Pacific Plate is moving northwest of the
North American Plate. Eventually California
will be further north.
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The Plates of the Earth

• There are two different types of plates that
  tectonic plates (earth plates) are made of
• Continental Plates
• and
• Oceanic Plates

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Continental and Oceanic Plates

• Continental plates are located on continents.
  They are mostly made of a type of rock called
  granite.
• Oceanic plates are located in the ocean. They
  are mostly made of a type of rock called basalt.

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Convergent Zones

• A convergent zone is where two plates collide
  into one another. Some crust is destroyed on
  impact.
• This happens when continental plates hit into
  each other, when oceanic plates hit into each
  other, and when a continental plate and an
  oceanic plate hit into each other.
• When two continental plates collide, the
  destroyed rock will pile on top of each other,
  forming a mountain.

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Subduction Zones

• Subduction zones occur at convergent zones (where
  two plates collide).
• Subduction zones refer to where one plate
  slides underneath another plate, forcing it into
  the mantle of the earth.
• Within the mantle there is hot, liquid rock
  called magma. This magma melts the subducted
  plate.

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An example of Subduction

• When oceanic plates collide with another oceanic
  plate or a continental plate, one may be pushed
  under the other causing magma to rise thus
  forming volcanoes.

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Where does the magma come from?

• Magma is melted rock located in the mantle of the
  earth.
• Another term for where magma is located is the
  asthenosphere.
• The asthenosphere is directly under the more
  solid upper mantle. This is where tectonic
  plates float.

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The Outer Layers of the Earth
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Convection currents

• Convecton currents take place in the
  asthenosphere.
• Convection currents allow heat energy to be
  transported throughout the mantle.
• Rocks within mantle will be somewhat melted due
  to high pressure.
• If pressure in the mantle is released, due to a
  crack in the earths surface, the rock will
  completely melt. This may result in magma
  forcing its way out of the earths surface in the
  form of a volcano.

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Convection Current models

• This movement of heat energy causes the tectonic
  plates to move.

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Theories

• The theory that convection currents cause
  tectonic plates to move is called the Tectonic
  Plate Theory.
• The theory that the earths lithosphere floats on
  top of the asthenosphere is called Continental
  Drift.

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Pangaea

• The theory of continental drift came about
  through a hypothesis that all the earths
  continents were once attached to each other.
• This supercontinent is called pangaea.
• Continental drift allowed these continents to
  slowly move apart from one another, to where the
  continents are now located.

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Pangaea- The Super Continent!